H3C S3600 Series Operation Manual

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Contents

H3C S3600 Series Operation Manual Manual pdf 8 page image

Operation Manual – DHCPH3C S3600 Series Ethernet Switches-Release 1510 Chapter 2 DHCP Server Configuration2-1Chapter 2 DHCP Server ConfigurationNote:The contents of this chapter are only applicable to the S3600-EI series among S3600series switches.2.1 Introduction to DHCP Server2.1.1 Usage of DHCP ServerGenerally, DHCP servers are used in the following networks to assign IP addresses:z Large-sized networks, where manual configuration method bears heavy load andis difficult to manage the whole network in centralized way.z Networks where the number of available IP addresses is less than that of the hosts.In this type of networks, IP addresses are not enough for all the hosts to obtain afixed IP address, and the number of on-line users is limited (such is the case in anISP network). In these networks, a great number of hosts must dynamically obtainIP addresses through DHCP.z Networks where only a few hosts need fixed IP addresses and most hosts do notneed fixed IP addresses.2.1.2 IRF SupportIn an IRF (intelligent resilient framework) system, DHCP servers operate in acentralized way to fit the IRF environment.z DHCP servers run (as tasks) on all the units (including the master unit and theslave units) in a Fabric system. But only the one running on the master unitreceives/sends packets and carries out all functions of a DHCP server. Thoserunning on the slave units only operate as the backup tasks of the one running onthe master unit.z When a slave unit receives a DHCP-REQUEST packet, it redirects the packet tothe DHCP server on the master unit, which returns a DHCP-ACK/DHCP-NAKpacket to the DHCP client and at the same time backs up the related information tothe slave units. In this way, when the current master unit fails, one of the slavescan change to the master and operates as the DHCP server immediately.z DHCP is an UDP-based protocol operating at the application layer. When a DHCPserver in a fabric system runs on a Layer 2 network device, DHCP packets are